Got it really bad last year while pulling some nasty weeds/vines out of my front yard (just bought the house last year). I had it really bad on my face, eyes swelled shut, etc. Went to the doctor, and he prescribed a treatment of Prednisone that I took for 9 days (6 pills first and second day, 5 pills third and fourth, 4 pills fifth and sixth, 3 pills day seven, 2 pills day eight, one pill day nine, and then all done).
Worked great, swelling/itching went away within 12 hours of taking the first dose.
Downside was I had terrible night sweats for about 2 weeks after. Would wake up soaking wet with cold sweat.
If I had to do it over again, I definately would!
Go to a doctor if you have it on your face, genitals, or any large blisters anywhere.
Whatever you do, don't listen to Rfeynman!